Refrigeratior having multiple section evaporator



April 10, 1956 J. w. JACOBS Filed Oct. 7. 1952 REFRIGERATOR HAVINGMULTIPLE SECTION EVAPORATOR 2 Sheets-Sheet l INVENTOR. James WJacobsApril 10, 1956 J. w. JACOBS 2,741,095

REFRIGERATOR HAVING MULTIPLE SECTION EVAPORATOR Filed Oct. 7, 1952 2Sheets-Sheet 2 INVENTOR. James W Jacobs BYWMMMQ United States Patent O lREFRIGERATOR HAVING MULTIPLE SECTION EVAPORATOR James W. Jacobs, Dayton,Ohio, assignor to General Motors Corporation, Detroit, Micln, acorporation of Delaware Application October 7, 1952, Serial No. 313,453

4 Claims. (Cl. 62-4) This invention relates to refrigerating apparatusand more particularly to a method and apparatus which facilitatesdefrosting both of the evaporators in a dual compartment refrigerator.

It is an object of this invention to provide a refrigerating systemwherein the frost which forms on the evaporators is allowed to thawduring the off portion of each refrigeration cycle.

More particularly it is an object of this invention to provide arefrigerating system wherein the'evaporator means comprises threedifferent sections connected in series refrigerant flow relationship andwherein two of the three evaporator sections are defrosted during eachott cycle.

Still another object of this invention is to provide a method andapparatus for defrosting that portion of the frozen food compartmentevaporator on which frost normally accumulates while maintaining themain food supporting shelf below freezing at all times.

A further objectof this invention is to divide the evaporator for thefrozen food compartment into two sections so as to make it possible todefrost the one evaporator section independently of the other.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings, wherein a preferred form of the present invention is clearlyshown.

In the drawings:

Figure 1 is a perspective view with parts broken away showing somewhatdiagrammatically a refrigerator constructed in accordance with myinvention; and,

Figure 2 is a schematic view showing the refrigerant circuit and thecontrols for the system.

Referring now to the drawings wherein a preferred embodiment of theinvention has been shown, reference numeral designates the outer shellof a refrigerator having a frozen food compartment 12 and an unfrozenfood compartment 14. For purposes of illustration there has been shown amultiple door refrigerator wherein a first door 16 is provided forclosing the front opening to the frozen food compartment 12 and a seconddoor 18 is provided for closing the front opening of the unfrozen foodcompartment 14. The invention is also applicable to a refrigerator inwhich a single door closes both compartments. I

The frozen food compartment 12 is adapted to be maintained in arefrigerated condition by means of a pair of plate type evaporatorsections 26 and 22. The evaporator section 20 is fiat and serves as thebottom for the frozen food compartment 12 and consequently it is indirect mechanical contact with the frozen foods stored in thecompartment 12. Experience shows that the bottom wall of the frozen foodcompartment is normally covered by frozen foods and therefore the topsurface of the evaporator section 20 is largely protected against theaccumulation of frost thereon.

The evaporator section 22 is bent so as to form the top and side wallsof the compartment 12. These are the 2,741,095 Patented Apr. 10, 1956walls where frost tends to accumulate and consequently they must bedefrosted from time to time. The inner surfaces of the evaporatorsection 22 are normally fully exposed to the air with the result thatmost of the excess moisture from the air tends to freeze on thesesurfaces.

In order to facilitate the drainage of defrost water from the surfacesof the section 22, the lower edges thereof are spaced from the adjacentedges of the evaporator section 20 so as to allow the defrost Water todrain into the condensate collecting pan 30 located directly below theevaporator sections 20 and 22 as shown in Figure 1. The arrangement issuch that the condensate water drains from the pan 30 through a drainpipe 32 into the main food storage compartment 14. The outlet of thedrain pipe 32 is located directly adjacent the one wall of thecompartment 14 as shown in Figure 1 whereby the drain water will flowdown the side wall of the compartment 14 and into a drain opening 34provided in the bottom wall of the compartment 14. The drain opening 34discharges the water into the condensate evaporating pan 36 locateddirectly over the condenser 38 so as to cause reevaporization of thewater into the condenser air stream in accordance with well knownpractice.

The food storage compartment 14 is refrigerated by means of a plate typeevaporator 40 mounted adjacent the upper rear corner of the compartment14. A trough 42 is provided directly beneath the evaporator 46 andserves to direct the condensate water down along the rear wall of thecompartment 14 in accordance with practice which is now well known inthe refrigeration industry. Suitable insulation 44 surrounds thecompartments l2 and 14 in the manner shown. The insulationwhich'surrounds the evaporator sections 20 and 2 2 is preferably of thetype enclosed within moisture proof plastic bags so as to prevent frostor moisture from permeating the insulation. There is no tendency formoisture damaging the insulation around the lower compartment 14 andconsequently any form of insulation can be used to insulate this lowercompartment.

It will be noted that the condensate collecting pan 30 separates theinsulation surrounding the compartment 12 from the insulationsurrounding the compartment 14. The pan 30 is large enough to collectany defrost water which occasionally may drain from the outer surfacesof the bags of insulation surrounding the frozen food compartment 12. Aslight clearance between the outer edges of the pan. 30 and the outerwall of the cabinet 19 constitutes a breather space whereby any excessmoisture in the lower part of the refrigerator is free to travelupwardly past the pan 30 and condense on the exposed and relatively coldsurfaces of the evaporator section 22.

Referring now to Figure 2 of the drawing wherein the refrigerant circuithas been diagrammatically shown, reference numeral 50 designates aconventional sealed motorcompressor unit which serves to dischargecompressed refrigerant through a line 52 into the condenser 38. Thecondensed refrigerant flows from the condenser 38 to a receiver anddryer receptacle 54 from whence liquid refrigerant is fed through acapillary tube type of restrictor 56.- The restrictor 56 feeds liquidrefrigerant at a reduced pressure into the plate type evaporator orevaporator section 20 so as to refrigerate the foods placed thereon.Excess refrigerant flows from the evaporator 213 through a trap 58 tothe evaporator 56 which is located in the compartment 14. Duringportions of the refrigeration cycle more liquid refrigerant will besupplied to the evaporators 20 and 40 than can be evaporated therein andthis extra liquid refrigerant then flows to the evaporator section 22and helps to maintain the required low temperature in the frozen foodcompartment 12. The vaporized refrigerant returns to the compressorthrough the suction line 69.

The motor-compressor unit 50 is controlled by means of a thermostat 62in thermal exchange relationship with the evaporator 29. The thermostat62 opens and closes a switch 64 located in the power line '66 whichleads to the motor-compressor unit 53*. The switch 64 is designed toclose the circuit when the temperature of the evaporator 48 exceeds apredetermined value such as 36 degrees. Once the switch 64 closes itwill remain closed until the temperature of the evaporator 44; drops toa predetermined low temperature such as'miiius 2 degrees. abovementioned temperature valu'eshave been given for purposes ofillustration and may be varied somewhat without departing from thespirit ofmy invention.

A secondary refrigerating system is used for refrigerating the bottomwall ofthe food storage compartment 14 and includes an evaporatorsection 74 arranged in thermal exchange relationship with the'hotto'mwall of the compartmentland a condensing section 72 arranged in thermalexchange relationship with the back of the evaporator 40.

By virtue of the above described primaryrefrigerant circuit theevaporator section 20 will be supplied with an adequate amount of liquidrefrigerant so as to prevent objectionable Warm-up of the frozen foodssupported thereon even during defrosting. The evaporator sections 40 and22 however will be starved during each 05 cycle to such an extent thatany frost which may have accumu- I-ated thereon during the on portion ofthe cycle will melt before another on cycle begins.

While the form of embodimentof the invention as hereindisclosed'constitutes a preferred form, it isto be understood that otherforms mightbe adopted, as may come within the scope of the claims whichfollow.

What is claimed is as follows:

1. In a refrigerator having a frozen-food storage compartment and anunfrozen food storage compartment, a first evaporator section formingthe bottom wall of said frozen food storage compartment, a secondevaporator section arranged in thermal exchange relationship with thecontents of said unfrozen food compartment, a third evaporator sectionarranged in the upper portion of said frozen food storage compartmentand connected to the outlet of said second evaporator section, saidfirst and third evaporator sections forming the bottom and side wallsrespectively of said frozen food storage compartment, said bottom walland said side walls being spaced from one another so as to preventconduction of heat from said side walls to said bottom wall, refrigerantliquefying means for supplying liquid refrigerant to said evaporatorsections, and means responsive to the temperature of said secondevaporator section for controlling the operation of saidrefrigerantliquefying'means.

, 2. In a refrigerator having an upper frozen food s't'or-,

age compartment and a lower unfrozen food storage compartment, a firstevaporator section forming the bottom Wall of said upper frozen foodstorage compartment, a second evaporator section arranged below saidfirst evaporator section in thermal exchange relationship with thecontents of said unfrozen food compartment, a third evaporator sectionarranged in the upper portion of said frozen food storage compartmentand comprising refrigerant The insulated from said bottom wall,refrigerant liquefying means for supplying liquid refrigerant to saidfirst evaporator section and thereafter said second and third evaporatorsections in series refrigerant flow relationship, means responsive tothe temperature of said second evaporator section for starting andstopping said refrigerant liquefying means, and means for trappingrefrigerant in said first evaporator section while said refrigerantliquefying means is stopped. v a

3. In a refrigerator having a frozen food storage compartment and anunfrozen food storage compartment, 21 first evaporator section formingthe bottom wall of said frozen food storage compartment, a secondevaporator section arranged in thermal exchange relationship with thecontents of said unfrozen food compartment, a third evaporator sectionarranged in the upper portion of said frozen food storage compartmentand comprising refrigerant conduit means adjacent the top and side wallsof said frozen food compartment, said top and side walls beinginsulatedfrom said bottom wall, refrigerant lique fying means forsupplying liquid refrigerant to said first evaporator section and thento said Second and third evaporator sections, means responsive to thetemperature of one of said latter evaporator sections for controllingsaid refrigerant liquefying means, said control means serving to stopsaid refrigerant liquefying means at a predetermined low temperature andto restart said refrigerant liquefying means at a predetermined highertemperature above the freezing temperature "of water whereby saidconduit means adjacent the top and side walls of said frozen foodcompartment, said side and top walls being one section warms up to adefrosting temperature before said refrigerant liquefying means restartsand condensate collecting means disposed beneath the vside walls of saidfrozen food compartmentfor receiving the defrost, water.

4. In' a refrigerator having afroz'en food storage compartment and anunfrozen food storage compartment, a first plate type evaporator sectionforming the bottom Wall of said frozen food storage com'partment, asecond evaporator section arranged in thermal exc'hangerelationship withthe contents of said unfrozen food compartment, a third plate typeevaporator section arranged in the upper portion of said frozen foodstorage compartment and forming side Walls of said frozen food storagecompartment, said first and third evaporator sections being out ofcontact with one another so as to substantially prevent the conductionof heat from one to the other, refrigerant liquefying means for suplyingliquid refrigerant to said evaporator sections in series refrigerantflow relationship, and means responsive to the temperature of saidsecond'evaporator section for controlling the operation of saidrefrigerant liquefying means, said second evaporator section beingconnected between said first and third evaporator sections.

References Cited in the file of this patent UNITED STATES PATENTS 72,260,825 Blood Oct. 28, 1941 2,578,906 Tobey Dec. 18, 1951 2,597,267Shoemaker May 20, 1952 2,617,268 Ashby Nov. 11, 1952 2,622,412 Staebler-z -2, Dec. 23, 1952 2,706,894 Shoemaker Apr. 22, 1955

